Molecular dynamics (MD) simulations were adopted to compare the enhanced mechanical and tribological properties of nitrile rubber composites reinforced by different functionalized graphene sheets. Functional groups such as hydroxyl (OH), carboxyl (COOH), and ester (COOCH₃) were adopted. The constant strain method was applied to measure the mechanical properties of graphene/nitrile rubber composites. Sandwiched molecular models were developed to investigate the tribological properties of graphene/nitrile rubber composites by applying a shear load. The MD simulation results showed that the incorporation of functionalized graphene enhanced the Young's modulus, bulk modulus, and shear modulus of the nitrile rubber matrix. In addition, the coefficient of friction and abrasion rate of the functionalized graphene/nitrile rubber composites decreased. The mechanisms for the interfacial interactions between the functionalized graphene and nitrile rubber matrix were determined by calculating the mean square displacement of rubber chains, binding energy, and the radial distribution function between functional groups and polar atoms in the rubber matrix, respectively. The results of the atomistic simulations indicated that stronger interfacial interactions and better stability and dispersion of graphene in rubber matrices can be obtained by introducing functionalized graphene. Owing to the combination of hydrogen bonding and strong van der Waals interactions, the COOH‐functionalized graphene behaves the best effect on the enhancement of mechanical and tribological properties of the nitrile rubber composites.

中文翻译：

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不同功能化石墨烯片增强丁腈橡胶复合材料力学和摩擦性能的比较研究：分子动力学模拟

通过分子动力学（MD）模拟比较了不同功能化石墨烯片增强的丁腈橡胶复合材料的增强的机械和摩擦学性能。官能团，例如羟基（ OH），羧基（ COOH），和酯（ COOCH ₃）被采用。采用恒应变法测量石墨烯/丁腈橡胶复合材料的力学性能。建立了夹层分子模型，通过施加剪切载荷来研究石墨烯/丁腈橡胶复合材料的摩擦学性能。MD模拟结果表明，官能化石墨烯的掺入提高了丁腈橡胶基体的杨氏模量，体积模量和剪切模量。此外，功能化石墨烯/丁腈橡胶复合材料的摩擦系数和磨损率降低。通过计算橡胶链的均方位移，结合能，碳原子数，确定官能化石墨烯与丁腈橡胶基体之间的界面相互作用机理。以及橡胶基质中官能团和极性原子之间的径向分布函数。原子模拟的结果表明，通过引入官能化的石墨烯可以得到更强的界面相互作用以及更好的石墨烯在橡胶基质中的稳定性和分散性。由于氢键和强范德华相互作用的结合，COOH官能化的石墨烯在增强丁腈橡胶复合材料的机械和摩擦学性能方面表现出最佳效果。